When subject to excessive thermal or mechanical stress, high energy density batteries (such as those in vehicular applications) can uncontrollably release their energy and explode or catch fire in a dangerous exothermic reaction called a thermal runaway. If several batteries are used in close proximity (which is normal for vehicles using battery power), the thermal energy generated by one damaged battery may transfer to others, causing those adjacent batteries to undergo the same exothermic reactions, thus propagating a chain of dangerous reactions.